It is daunting to take up the review of a 650-page book that presents 21 chapters covering the gamut of interests that absorb modern marine geochemists. Offsetting that challenge is the potential reward of gaining a deep appreciation of modern marine geochemistry from the writings of experts. This book dazzles. Given the eminence of authors who have written these chapters, one expects a high level of science, but the presentation also achieves an exceptional and sustained quality of clarity both in text and figures. The cover picture of two carbonate-sequestering species, a coccolith and a foram, together with a dedication to Harmon Craig, John Edmond and Ceasare Emiliani, leads the reader to expect carbonate to occupy a rather large part of the book, and so it does. But this book is much more than that.

Focused predominantly on the blue ocean, topical chapters include physical chemistry (Ch. 6.01), trace metal cycling (Chs 6.02, 6.05), gases in seawater (Ch. 6.03), particle processes and the biological pump (Chs 6.04, 6.09, 6.10, 6.18), organic matter cycling and the application of alkenones to thermometry (Chs 6.06, 6.15), hydrothermal processes (Ch. 6.07), the application of tracers to ocean mixing (Ch. 6.08), sediment diagenesis (Ch. 6.11), geochronometry of marine deposits (Ch. 6.12), quite a few chapters examining past oceans and ocean processes as reflected by a wide range of isotopic and elemental tracers (Chs 6.13, 6.14, 6.16, 6.17, 6.20, 6.21), and one chapter looking exclusively at CaCO3 in the ocean (Ch. 6.19). Although each chapter may be read in isolation, I would recommend anyone interested in a particular topic to peruse the index and read the three or four chapters that pertain, as each chapter offers a different emphasis and different approach.

In my mind, several chapters stand out. In ‘Tracers of ocean mixing’, Jenkins presents an exceptionally lucid description of how chemical tracers are applied in models to derive insight on mixing scales and transport timeframes. The mathematics, which easily could overwhelm such a chapter, is presented in a straightforward and simple fashion, as is the role and importance of chemical clocks and tracers in validating mixing models. Reading this chapter will not make you a modeller, but it will instill in you an understanding of the achievements and limitations of models, and would be highly recommended reading for any geochemical graduate student. Geochronology, one of the pillars of marine geochemistry, provides the basis for setting environmental studies into the context of time; accordingly, no geochemist can afford to be without a fundamental understanding of the applications and limitations of geochemical clocks. Turekian & Bacon (‘Geochronometry of marine deposits’) note that ‘all absolute dating methods that have proven dependable are based on radioactive decay’. This statement then provides the context for a chapter whose content-to-length ratio is exceptionally large. Again, I would assign this chapter as compulsory graduate reading. The two chapters on the biological pump (de la Rocha for the modern pump and Sigman & Haug for the pump in the past) form a compelling back-to-back read. The first chapter provides a solid description of how the biological pump may control P, N and Si cycling in the ocean. The second chapter is a wonderful discussion of how the biological pump may – or may not – solve geochemical conundrums like atmospheric CO2 drawdown during glacial periods. Indeed, I would assign this chapter pair as an introduction to linking biogeochemical cycles and to start a student down the path of thinking like a geochemist. Likewise, the chapter by Goldstein & Hemming provides an elegant suite of figures to present complex isotopic data. In particular, they bring to this chapter an emphasis on ‘tools not currently considered as “conventional” tools for oceanographic, paleoceanographic, or paleoclimate studies’. I also found the perspective on organic matter in the contemporary ocean (Eglinton & Repeta) to provide a concise overview of the problems of preservation of organic carbon and teasing records out of organic remains sequestered in sediments and rock, summarized with a helpful set of proposed tasks for future research. I could go on as each chapter has much of merit!

A very appealing aspect of this book is the clear exposition of the enormous scope of Earth's history to which geochemical techniques may be applied. Perhaps appropriately, the last chapter by Holland looks at the long-term geological history of seawater, going back 4 Ga. Here, the requirement of dating control together with elemental and isotopic cycling constraints leads to intriguing conjectures and many remaining puzzles. We know the Earth's ocean has changed dramatically at times in the past, but we remain woefully uncertain about how and why the changes occurred. At the start of this chapter, Holland notes that Aristotle assigned the saltiness of the sea to the effect of sunlight. Some 330 years ago, Robert Boyle set out to replace this conjecture with one based on data and I suppose Holland's chapter continues the dialectic argument to refine understanding through new measurements. As is pointed out in this and other chapters, the first inferences from new elemental and isotopic data, for example stable Pb isotope measurements achieved by Patterson several decades ago, have often proven to be wrong (or incomplete) and, as more data are acquired, these flawed concepts, useful as booster stages, have been discarded to be replaced by newer concepts. Time and again, chapters in the book hint at concepts formed years or decades ago that have only recently become testable due to the spectacular improvement in sampling and instrumentation during the past two decades. Simple ideas, like the application of Mg/Ca palaeotemperature proxy to benthic foraminifera, often prove ‘more complicated than initially assumed’ (Ravizza & Zachos, Ch. 6.20) and considerable space in the book is consigned to discussing the often tortuous path to developing an incisive proxy. Geochemists undoubtedly stand on the shoulders of giants. Accordingly, most of the chapters in this book present ‘a work in progress’ as evident by the large proportion of recent citations (over 40% dating from 1996 to 2003), with only one chapter (‘Physicochemical controls on seawater’ by Millero) presenting the topic as ‘classical’. I consider the heavy weighting of recent findings a strength of this book, and the ‘unfinished business’ provides immense scope for the next generation of geochemists. About the time this book was being finalized, Steven Weinberg advised aspiring graduates ‘to go for the messes – that's where the action is’ (Commencement address at McGill University 2003). In many of the chapters, especially those dealing with what the Earth's archives have to instruct us about past climates, the understanding remains very messy. Clearly, an astute student can use this book to find something of career-making potential.

This book provides excellent introductory material for a student, or anyone, who wants to catch up on modern ocean geochemical topics, and I know I will value it as a reference for some time. There are some weaknesses, perhaps highlighted when you read the book cover to cover as I have done. There are many places where topics are discussed in more than one chapter, almost invariably without inter-chapter citations. For example, Bruland & Lohan (Ch. 6.02, ‘Controls of trace metals in seawater’) have clearly read and appropriately refer to Morel et al.’s chapter (Ch. 6.05, ‘Marine bioinorganic chemistry’) whereas the converse is not true. Both chapters present a few parallel or identical diagrams and would have been improved by better cross-citing. Likewise, the topic of denitrification together with reaction schemes is presented in two places (one better than the other), Mg/Ca as a palaeothermometer is discussed in at least four chapters, and boron and 11B/10B as a palaeo-pH recorder in three chapters, all without reference to each other; the list is long. Clearly some overlap of material is required to make chapters self-contained and, indeed, I found it instructive to compare the views of different experts. However, there are many places in this book where the authors of a chapter cite journal literature to make a particular point when they could better have directed the reader to the next or last chapter for a detailed discussion and/or figure.

The content of the book, which is primarily about elemental cycling, isotopes and palaeorecords, is what I'd term ‘biogeochemistry’. One chapter looks specifically at organic carbon as a source of proxy information (Ch 6.06, ‘Organic matter in the contemporary ocean’) and a second at the application of alkenones to palaeothermometry (Ch 6.15). Nevertheless, this book is not, and does not claim to be, an organic geochemical treatise. In many places the benefit of multiple proxies is emphasized such that I was disappointed that in only a very fewplaces was any attempt made to put standard geochemical markers (elements and isotopes) together with organic biomarkers. Perhaps this is a task for the future. Being interested in the Arctic, I was also disappointed in how little the Arctic Ocean has factored in the development of marine geochemical concepts as espoused in the book. This seems strange and perhaps the looming International Polar Year will set to rights this gap.

I also found the hierarchical subject index a bit of a struggle. For example, if you are interested in Redfield Ratio, you will have to go through the entire index to tease out where it appears (at least three times as Redfield Ratio and about five times as C:N:P). Even if you do that, you will by no means catch all of the references to this ratio in the chapters. The text contains but a handful of ‘typos’, only one where the meaning was obscured. There are a couple of hard-to-read figures and one or two where labelling is so thin as to make them not understandable. I do not want to end my review of this brilliant book with criticism: I highly recommend it and every chapter in it.